The present invention resides generally in the field of regulation of myeloid cells such as stem cells or progenitor cells. More particularly, the present invention relates to the suppression of myeloid cells using chemokines.
As further background, accessory cell-derived cytokines regulate proliferation/differentiation of hematopoietic stem and progenitor cells in vitro and in vivo. See, Broxmeyer, et al., "The Production of Myeloid Blood Cells and Their Regulation During Health and Disease", CRC Crit. Rev. Oncol/Hematol., Vol. 8, p. 173 (1988); and Broxmeyer, "Biomolecule-cell Interactions and the Regulation of Myelopoiesis, An Update", in Murphy Jr. (ed): Concise Reviews in Clinical and Experimental Hematology, Dayton, Ohio, Alpha Med Press, p. 119 (1992). Cytokines can have stimulating, enhancing, and/or suppressing activities mediated either directly on stem/progenitor cells and/or indirectly on accessory cells.
A number of cytokines have been implicated in negative regulation. See, Broxmeyer, et al., "The Production of Myeloid Blood Cells and Their Regulation During Health and Disease", supra; Broxmeyer, "Biomolecule-cell Interactions and the Regulation of Myelopoiesis, An Update", supra; and Broxmeyer, "Suppressor Cytokines and Regulation on Myelopoiesis: Biology and Possible Clinical Uses", Amer. J. Ped. Hematol/Oncol., Vol. 14, p. 22 (1992). Suppression can be mediated by biological molecules termed cytokines, such as macrophage inflammatory protein (MIP)-1.alpha., a heparin binding protein originally identified by its capacity to cause a localized inflammatory reaction after injection into the footpads of C3H/HeJ mice. See, Wolpe, et al., "Macrophages Secrete A Novel Heparin-Binding Protein with Inflammatory and Neutrophil Chemokinetic Properties", J. Exp. Med., Vol. 167, p. 570 (1980); Davatelis, et al., "Cloning and Characterization of a cDNA for Murine Macrophage Inflammatory Protein (MIP), a Novel Monokine with Inflammatory and Chemokinetic Properties", J. Exp. Med., Vol. 167, p. 1939 (1988); and Sherry, et al., "Resolution of the Two Components of Macrophage Inflammatory Protein 1, and Cloning and Characterization of One of Those Components, Macrophage Inflammatory Protein 1.beta.", J. Ext. Med., Vol. 168, p. 2251 (1988).
MIP-1.alpha., but not a closely related family member MIP-1.beta. suppressed proliferation of a subset of murine (mu) stem cells (day 12 colony forming-unit-spleen (CFU-S)) ex vivo and mu colony forming unit-A (an apparently early progenitor cell) (see, Graham et al., "Identification and Characterization of an Inhibitor of Hematopoietic Stem Cell Proliferation", Nature, Vol. 334, p. 442 (1990)), as well as mu and human (hu) growth-factor stimulated multipotential (CFU-GEMM), erythroid (BFU-E) and granulocyte macrophage (CFU-GM) progenitor cells (see, Broxmeyer, et al., "Enhancing and Suppressing Effects of Recombinant Murine Macrophage Inflammatory Proteins on Colony Formation in vitro by Bone Marrow Myeloid Progenitor Cells", Blood, Vol. 76, p. 1110 (1990)) in vitro. Suppressive effects of MIP-1.alpha. were apparent on more immature populations of progenitors which were stimulated to proliferate by a combination of two or more early acting growth stimulating cytokines. See, Broxmeyer, et al., "Enhancing and Suppressing Effects of Recombinant Murine Macrophage Inflammatory Proteins on Colony Formation in vitro by Bone Marrow Myeloid Progenitor Cells", Blood, Vol. 76, p. 1110 (1990); and Bodine, et al., "Effects of Hematopoietic Growth Factors on the Survival of Primitive Stem Cells in Liquid Suspension Culture", Blood, Vol. 78, p. 914 (1991). These effects appeared to be directly on the progenitors themselves. See, Broxmeyer, et al., "Macrophage Inflammatory Protein (MIP)-1.beta. Abrogates the Capacity of MIP-1.alpha. to Suppress Myeloid Progenitor Cell Growth", J. Immunol., Vol. 147, p. 2586 (1991). MIP-1.alpha. did not suppress proliferation of the more mature progenitors which were stimulated to proliferate by a single cytokine. See, Broxmeyer, et al., "Enhancing and Suppressing Effects of Recombinant Murine Macrophage Inflammatory Proteins on Colony Formation in vitro by Bone Marrow Myeloid Progenitor Cells", supra; and Broxmeyer, et al., "Macrophage Inflammatory Protein (MIP)-1.beta. Abrogates the Capacity of MIP-1.alpha. to Suppress Myeloid Progenitor Cell Growth", supra.
MIP-1.alpha. has recently been shown to have in vivo suppressive effects on cycling rates of CFU-S, CFU-GEMM, BFU-E and CFU-GM when administered to mice (see, Maze, et al., "Myelosuppressive Effects in vivo of Purified Recombinant Murine Macrophage Inflammatory Protein-1 Alpha", J. Immunol., Vol. 149, p. 1004 (1992); Dunlop, et al., "Demonstration of Stem Cell Inhibition and Myeloprotective Effects of SCI/rhMIP-1.alpha. in vivo", Blood, Vol. 79, p. 2221 (1992); and Lord, et al., "Macrophage-Inflammatory Protein Protects Multipotent Hamatopoietic Cells from the Cytotoxic Effects of Hydroxyurea in vivo", Blood, Vol. 79, p. 2605 (1992)), and in this context was myeloprotective for the drugs cytosine arabinoside (see, Dunlop, et al., supra) and hydroxyurea (see, Lord, et al., supra.) MIP-1.beta. was not myelosuppressive in vivo. See, Maze, et al., supra.
MIP-1.alpha. also inhibited proliferation of an unstimulated cytotoxic T-cell line, CTLL-R8 (see, Oh, et al., Identification of Cell Surface Receptors for Murine Macrophage Inflammatory Protein-1.alpha.", J. Immunol., Vol. 147, p. 2978 (1991)), and modulated macrophage function, including induction of the release of tumor necrosis-factor, interleukin (IL)-1.alpha. and IL-6 in vitro. See, Fahey, et al., "Macrophage Inflammatory Protein 1 Modulates Macrophage Function", J. Immunol., Vol. 148, p. 2764 (1992). MIP-1.beta., when present in excess compared to MIP-1.alpha. in vitro, blocked both the suppressive effects of MIP-1.alpha. on myeloid progenitors (see, Broxmeyer, et al., "Macrophage Inflammatory Protein (MIP)-1.beta. brogates the Capacity of MIP-1.alpha. to Suppress Myeloid Progenitor Cell Growth", supra), and the cytokine-inducing effects of MIP-1.alpha. on macrophages. See, Fahey, et al., supra.
MIP-1.alpha. and MIP-1.beta. are members of a larger family of molecules variously termed small inducible proteins, intercrine cytokines (see, Wolpe, et al., "Macrophage Inflammatory Proteins 1 and 2: Members of a Novel Superfamily of Cytokines", FASEB J., Vol. 3, p. 2565 (1989); Oppenheim, et al., "Properties of the Novel Proinflammatory Supergene `Intercrine` Cytokine Family", Ann. Ref. Immunol., Vol. 9, p. 617 (1991); and Schall, "Biology of the Rantes/Sis Cytokine Family", Cytokine, Vol. 3, pp 165 (1991)), and more recently, chemokines. They are linked by amino acid homology, chromosome location and the presence in their primary sequence of 4 position invariant cysteine residues. The hu MIP-1 family, located on chromosome 17 and having a c-c motif, includes MIP-1.alpha. (=LD78), MIP-1.beta. (=Act 2), Macrophage Chemotactic and Activating Factor (MCAF=muJE) and RANTES. The hu MIP-2 family located on chromosome 4 and having a c-x-c motif, includes GRO-.alpha. (also called melanoma growth stimulating factor=muKC), MIP-2.alpha. (=GRO-.beta.), MIP-2.beta. (=GRO-.gamma.), Platelet Factor 4 (PF4), Interferon Inducible Protein-10 (IP-10), IL-8 (=neutrophil activating peptide (NAP)-1), and NAP-2 (which derives from platelet basic protein an its derivatives connective tissue activating peptide III and .beta.-thromboglobulin).